Biggest astrophotography Mistakes : The 7 mistakes you need to avoid
Getting beautiful images of the night sky requires good preparation and excellent manipulation of your telescope. It requires also to avoid some mistakes that can ruin you astrophotogarphy sessions.
In this article you’ll find the biggest astrophotograpy mistakes that you must avoid in order to obtain excellent planetary and deep sky object images.
1 – Don’t balance your scope
Balancing your scope is a very important step. It will first facilitate the manipulation of your telescope in order to point it to a desired region of the sky and also it will help the mount’s motors to work smoothly. If you scope isn’t well balanced it can have a negative impact on the performance on your motors of the right ascension and declination axises as they will work hardly to try to oriente correctly the telescope. On the long terme it will reduce the lifetime of the motors !
A non balanced scope will have also a bad impact on the performance and precision of the autoguiding. So for long exposure it will be hard to obtain a good results.
Balancing the scope is a very step, all you have to do is move counter-weight up or down on the RA axies until your scope stay in a fixed position when you release the mount brakes. Also you should consider to have the correct total weight of the counter-weight so you can balance the telescope correctly. For example, if we add the weight of the telescope + the camera + the finderscope and total is 6 kg, the counterweight should have the same value. If not you have to consider buying additional counter-weight like this one :
2 – Start shooting immediately before temperature balance
Your telescope is generally stored indoor. It can be inside your home, or even if your are lucky in your own observatory. No matter where it’s placed, the temperature of outdoor and indoor is always different and this difference has a huge impact on your astrophotography session.
When the temperature of your telescope is different from the temperature of its external environement, that causes a turbulence inside it, especially if the scope is a Newtonian or Dobsonian one. This turbulence will has a negative effect on your imagse because they will be blury no matter you try to fix the focus or collimation.
So our advice is to always let your telscope to a minium 30 minutes to 2 hours outside before you start your astrophotography imaging session. The exact duration depends on how much the temperature difference is, and the model of the scope (Newtonian, Dobsonian, Maksutov, …).
Some telescopes integrate a fan on back of the primary mirror in order to accelerate the temperature balance. It could be a good idea if you don’t want to spend a long time waiting for that. If you have big scope you can always easly add a mount like this one :
3 – Don’t polar align correctly and precisely
Plar alignment is certainely the most important step in Astrophotography, especially when photographing the Deep Sky. When imaging deep sky objects, you need to make a long exposure, from some seconds to some minutes, depending on objects, your scope, your location and the light pollution, …
And in order to obtain a clean images with perfect round stars, your polar alignment should be as perfect as possible.
There are many solutions to achieve an excellent polar alignement :
- Using a polar scope
A polar scope is an object that you can fix to your mount. It really facilitate the polar alignement step as it can be done in just few minutes and in addition the precision is pretty good. Personaly, with my Neq3-2 i’m able to shoot up to 60 seconds and the stars are perfectly round!
Here are some amazing polar scopes that you can fix to your telescope mount :
- Using the PoleMaster solution by QHYCCD
QHYCCD PoleMaster is probably the easiest and simplest way to do polar alignement ! With this device you can say goodbye to neck pai, ankle and muscle strain during polar alignment. All you have to do is to insert this special camera in you the polar scope holder, and do the polar alignement from the computer.
In addition, the accuracy is incredible : up to 30 arcseconds in just 5 minutes!
QHYCCD PoleMaster works on all tracking mounts and also at northern and southern hemisphere with atmospheric refraction correction.
4 – Don’t check your collimation
The position and orientation of your primary and secondary mirrors of your telescope is really important. Any shift or non-alignment of them can have a bad impact on your image quality. Checking their correct alignement is what we call Collimation.
Verifying the collimation of your telescope is adviced be done before every astrophotography session. And please keep in mind that if you move or travel with your telescope in car for example, you have to inevitably check your collimation again beause traveling will generate vibration that will decollimate your scope.
The collimation is a very easy step, it can be done in just few seconds with one of this 2 tools :
A Cheshire eyepiece, or Chechire collimator, is a tool that helps you quicly to check and align the optical axes of the mirrors (primary and secondary) of your telescope. All what you have to do is to insert it in the eyepiece holder and adjust the orientation of the mirrors using the set screws.
This collimation Cheshire eyepiece is ideal for newtonian telescopes as it allow optimal collimation.
With a Laser collimator the collimation become a really simple game. You can collimate your telescope in just few seconds without even looking the eyepiece. It’s mostly useful for adjusting the secondary mirror as it’s a little bit harder to do it with simple Cheshire eyepiece specially if you have a long tube / telescope.
4 – Don’t focus correctly
Sometimes we are so excited to start to image and to enjoy the beauty of night sky that we can overlook to focus correctly. Or we thought that we have focused perfectly but the optimal focus point is not reached. To achieve an excellent focus and quickly you can use a Bahtinov Mask :
Bahtinov masks take the guesswork out of focusing and even get over the seeing conditions as it is a mathematical type approach to the task. The best focus for your telescope quickly and easily.
5 – Don’t level your mount
Many astrophotographers don’t pay attention to the mount level, but this step is really important in order to achieve a good balance of the scope, a good polar alignment precision and even an excellent autoguiding. However, leveling your telescope mount is certainely the easiest step in astrophotography! It can be done in just few seconds no matter your mount.
To level your telescope mount, all you need to use is a level tool. Some mounts integrate already a level, but if yours doesn’t you can simply use a level like these ones :
or this one :
Then all you have to do is to put the level on your tripod (without mounting the mount). Next you have to adjust the length of each leg of your tripod separtely until the level is done.
6 – Shoot objects at the wrong season
In each season there are the perfect night sky object to shoot. The Planets for example there are what we call Planet opposition, that occurs when the planet is nearest to our earth. At this moment planets have their maximum angular size, and that’s the ideal period to shoot them. Mars planet for example has it opposition each 2 years and its size vary from 3.49″ to 25.13″ !
Angular diameter of planets
|Celestial body||Angular diameter or size|
|Venus||9.67″ – 1′3″|
|Jupiter||29.80″ – 50.59″|
|Saturn||14.50″ – 21.37″|
|Mars||3.49″ – 25.13″|
Also you have to choose the right time to image the planet. The perfect timing is when the planet is the highest in the sky, when it appoaches the zenith. In this position you’ll have less impact in term of atmospheric turbulence and less bad effect of light pollution.
For deep sky objects there’s no opposition, but there are seasons. Some objects have to be shot ideally in Winter, others in Summer and that depend on when they are close to zenith late at night.
To know which object you can shoot depending on the season or month, you can buy a book like this one :
In addition to the month-by-month guides, this book includes an introduction to the planets, sky and constellation maps, moon and meteor calendars, and ecliptic charts. An appendix includes a glossary, the Greek alphabet, the constellation genitives, common asterisms, software and internet sources, and much more. The small and light format makes this book the ideal portable reference.
7 – Don’t check batteries (DSLR, Computer, Mount)
What can be more frustrating than beeing in the middle of an astrophotography session and your battery of your camera, your computer or even your mount is out of power! You have to always check the battery status of all your equipment before taking out your instruments.
Think also of having secondary battery if possible for your camera (DSLR). If you are far from a power source, and this happens generaly for us as astronomers to avoid light pollution, think of having a Power tank :
This device can power up your computer, your mount your cameras and other accessories. It has a power of 7-amp hour.
- Two 12V output cigarette lighter ports
- Built-in flashlight with red filter cap
- Energy efficient LED spotlight
- Booster terminal on rear side
- Built-in Circuit Breaker for safety
- Cigarette lighter adapter included
- 110 V/220 V switchable universal AC adapter included
That was the 7 biggest mistakes you must avoid when practicing astrophotography and avoiding them will let have the best results in astrophotography. If you think that i forgot other tips feel free to share it in the comments.